The Finn set the best time of the day on a short run with the soft tyre during the afternoon running, which was extended by 30 minutes to make up for a delay caused by track repairs around lunchtime.
Raikkonen had attacked the run from the moment he left the pits, choosing to force a way past the Caterham of Charles Pic on his out lap rather than back off to get clear track.
After the short, but clearly committed run, the 2007 world champion switched back to longer runs.
Raikkonen's lap was just enough to prevent Force India hopeful Jules Bianchi from leading the way as he bids to earn a promotion to a race seat with the Silverstone-based team.
Bianchi's lap, which came just after the track re-opened following the long stoppage in the middle of the day, also came on soft tyres.
The Ferrari junior had no chance to respond to Raikkonen's lap, as he handed the Force India back to lead driver Paul di Resta for the final two hours.
World champion Sebastian Vettel was third fastest for Red Bull on a day where he focused on long runs with the medium and hard tyres.
Sauber's Esteban Gutierrez managed to go fourth with a short run, but he spent most of his afternoon getting used to how the Pirelli tyres behave on longer stints.
A series of short runs on the soft tyre helped Jean-Eric Vergne move up to fifth late in the day, moving him ahead of Lewis Hamilton.
The Briton had a much better second day with his new team, making up for his lack of running on Wednesday due to a crash by logging the most laps of anyone.
New Ferrari development driver Pedro de la Rosa got back out in the afternoon after a gearbox problem stopped the F138 in the morning. The Spaniard completed 50 laps.